• Acacia P. Miller, 1754
• Acacia abbreviata Maslin
• Acacia abietina Willd. accepted as Acacia linifolia (Vent.) Willd.
• Acacia abrupta Maiden & Blakeley
• Acacia abyssinica Benth.
• Acacia abyssinica sensu auct. accepted as Acacia sieberiana DC.
• Acacia acanthaster Maslin
• Acacia acanthocarpa Willd. accepted as Mimosa aculeaticarpa Ortega
• Acacia acanthoclada F. Muell.
• Acacia acantholoba Willd. accepted as Mimosa acantholoba (Willd.) Poir.
• Acacia acanthophylla (Britton & Rose) Standl. accepted as Acacia hayesii Benth.
• Acacia acapulcensis Kunth accepted as Lysiloma acapulcense (Kunth) Benth.
• Acacia acatlensis Benth.
• Acacia accola Maiden & Betche accepted as Acacia adunca G. Don
• Acacia acellerata Maiden & Blakeley
• Acacia acicularis R. Br. accepted as Acacia brownii (Poir.) Steud.
• Acacia acicularis Willd. accepted as Acacia farnesiana (L.) Willd.
• Acacia acinacea Lindl.
• Acacia aciphylla Benth.
• Acacia acoma Maslin
• Acacia acradenia F. Muell.
• Acacia acradenia F. Muell., p.p. accepted as Acacia umbellata Benth.
• Acacia acrionastes Pedley
• Acacia acuaria W. Fitzg.
• Acacia aculeatissima J.F. Macbr.
• Acacia aculeiformis Maslin
• Acacia acuminata auct. non Benth., p.p. accepted as Acacia lasiocalyx C.R.P. Andrews
• Acacia acuminata Benth.
• Acacia acutata W. Fitzg.
• Acacia acutifolia Maiden & Blakeley accepted as Acacia myrtifolia (Sm.) Willd.
• Acacia adansonii Guill. & Perr. accepted as Acacia nilotica (L.) Delile
• Acacia adenantheroides M. Martens & Galeotti accepted as Mimosa adenantheroides (M. Martens & Galeotti) Benth.
• Acacia adenocalyx Brenan & Exell
• Acacia adenogonia (Pedley) R.S. Cowan & Maslin
• Acacia adenophora Spreng.
• Acacia adhaerens Benth.
• Acacia adiantoides Spreng. accepted as Piptadenia adiantoides (Spreng.) J.F. Macbr.
• Acacia adinophylla Maslin
• Acacia adnata F. Muell.
• Acacia adonsonii Guill. & Perr. accepted as Acacia nilotica (L.) Delile
• Acacia adoxa Pedley
• Acacia adstringens (Schum. & Thonn.) Berhaut accepted as Acacia nilotica (L.) Delile
• Acacia adstringens Mart. accepted as Stryphnodendron adstringens (Mart.) Coville
• Acacia adsurgens Maiden & Blakeley
• Acacia adunca auct. non G. Don accepted as Acacia forsythii Maiden & Blakeley
• Acacia adunca G. Don
• Acacia aemula Maslin
• Acacia aestivalis E. Pritz.
• Acacia affinis Sweet accepted as Acacia dealbata Link
• Acacia alata R. Br.
• Acacia alba (Rottler) Willd. accepted as Acacia leucophloea (Roxb.) Willd.
• Acacia alba Colla accepted as Zapoteca portoricensis (Jacq.) H.M. Hern.
• Acacia albicans Kunth accepted as Havardia albicans (Kunth) Britton & Rose
• Acacia albicorticata Burkart
• Acacia albida Delile accepted as Faidherbia albida (Delile) A. Chev.
• Acacia albizioides Pedley
• Acacia alcockii Maslin & Whibley
• Acacia alemquerensis Huber
• Acacia alexandri Maslin
• Acacia alleniana Maiden
• Acacia allenii D.H. Janzen
• Acacia alpina F. Muell.
• Acacia altiscandens Ducke
• Acacia amaliae Domin accepted as Acacia oswaldii F. Muell.
• Acacia amanda G.J. Leach
• Acacia amara Willd. accepted as Albizia amara (Roxb.) B. Boivin
• Acacia amazonica Benth.
• Acacia ambigua Rose accepted as Acacia bilimekii J.F. Macbr.
• Acacia ambigua Vogel accepted as Lysiloma ambigua Urb.
• Acacia amblygona Benth.
• Acacia amblyophylla F. Muell.
• Acacia amboensis Schinz accepted as Acacia sieberiana DC.
• Acacia amentacea DC.
• Acacia amentifera F. Muell.
• Acacia americana Stokes accepted as Gleditsia triacanthos Linnaeus
• Acacia ammobia Maconochie
• Acacia ammophila Pedley
• Acacia amoena auct. non Wendl. accepted as Acacia rubida A. Cunn.
• Acacia amoena Wendl.
• Acacia ampeloclada Rusby
• Acacia ampliata R.S. Cowan & Maslin
• Acacia ampliceps Maslin
• Acacia amputata Maslin
• Acacia amyctica R.S. Cowan & Maslin
• Acacia amythethophylla A. Rich.
• Acacia anarthos Maslin
• Acacia anasilla A.S. George
• Acacia anastema Maslin
• Acacia anaticeps Tindale
• Acacia anceps DC.
• Acacia anceps Hook. accepted as Acacia complanata Benth.
• Acacia ancistrocarpa Maiden & Blakeley
• Acacia ancistroclada Brenan
• Acacia ancistrophylla C.R.P. Andrews
• Acacia andamanica I.C. Nielsen
• Acacia andongensis Hiern
• Acacia andrewsii W. Fitzg.
• Acacia anegadensis Britton
• Acacia aneura auct. non Benth. accepted as Acacia quadrimarginea F. Muell.
• Acacia aneura Benth.